Method for operating a dishwasher

ABSTRACT

A method for operating a dishwasher is provided. A heated fluid is at least periodically applied to items to be washed that are supported in an interior of the dishwasher. In order to heat the fluid, air is first conducted through a drying material suitable for exothermic drying. Thereafter, the air, together with the heated fluid driven out of the drying material, is conducted through an outlet opening through which the air, together with the heated fluid driven out of the drying material, enters the interior of the dishwasher. The outlet opening is cooled.

The invention relates to a method for operating a dishwasher, in particular a household dishwasher, according to the preamble of claim 1.

Dishwashers with what are known as sorption drying systems for the exothermic drying of cleaned items are known from DE 103 774 A1, DE 103 53 775 A1 and DE 10 2005 004 096 A1. Here in a sub-program step “drying” of the respective dishwasher program of the dishwasher moist air from the interior of the dishwasher serving as a washing container is conducted through a sorption container to dry items being washed by means of a fan and moisture is extracted out of the air being passed through by the reversibly dehydratable drying material in the sorption container. The reversibly dehydratable drying material is heated to very high temperatures to regenerate or in other words desorb the drying material. Water stored in said drying material therefore exits as hot water vapor and is conducted by an air flow generated by the fan into the washing container. This allows fluid and/or dishes present in the washing container as well as the air present in the washing container to be heated. Such a sorption drying system has proven extremely advantageous for energy saving and gentle drying of the dishes. However an outlet opening, through which air together with the fluid driven out of the drying material enters the interior, can become very hot, in particular when moisture is driven out of the drying material, so the outlet opening presents a source of risk for an operator.

The object of the invention is to remedy this situation.

The invention is based on a method for operating a dishwasher, in particular a household dishwasher, wherein at least items to be washed supported in an interior are subjected at least periodically to the action of heated fluid, whereby to heat the fluid air is first conducted through a drying material suitable for exothermic drying and then the air together with the heated fluid driven out of the drying material is conducted through an outlet opening, through which air together with the fluid driven out of the drying material enters the interior.

According to the invention provision is made for the outlet opening to be cooled. This reliably prevents the outlet opening becoming excessively hot and therefore a heated outlet opening does not present a source of risk of burns for an operator, when said operator opens the interior of a dishwasher, in order for example to interrupt the sequence of a wash program and eliminate problems caused for example by blockages of a filter or blocked spray arms.

According to one development provision is made for the outlet opening to be wet with a cooling agent, in particular with a cooling agent containing water, for cooling purposes. This allows cooling to be achieved with a freely available cooling agent in a particularly simple manner, the disposal of said cooling agent being problem-free.

In one development provision is made for the cooling agent to be circulated in a closed circuit. The cooling agent requirement is thus kept to a minimum.

In one development provision is made for the cooling agent to be circulated by means of a circulation pump to apply fluid to items to be washed. No further drive means are therefore required, which means that the number of components and the space required by all the components of the dishwasher are not increased.

In one development provision is further made for the circulation pump to be operated at a lower speed when the outlet opening is cooled than when fluid is applied to the items to be washed. During operation at a lower speed fluid is applied essentially to the outlet opening alone, thereby resulting in particularly intensive cooling.

In one development provision is made for air from the interior to be conducted in a closed circuit through the drying material and back through the outlet opening into the interior. This ensures that no air exits from the dishwasher and is able for example to damage adjacent furniture.

In a further development provision is made for there to be a forced throughflow through the drying material. This increases efficiency when driving fluid out of the drying material.

To this end in one development provision is made for bringing about a forced throughflow by means of a fan.

To this end in one development provision is made for a reversibly dehydratable drying material, in particular zeolite, to be used. This drying material is characterized by a particularly high water absorption capacity and by a particularly good reversible dehydration capacity.

The object of the invention is further achieved by a dishwasher, in particular a household dishwasher, at least featuring means for subjecting items to be washed supported in an interior of the dishwasher at least periodically to the action of heated fluid, with a drying material suitable for exothermic drying being provided to heat the fluid, through which drying material air can be conducted and then the air together with heated fluid driven out of the drying material can be conducted into the interior (IR), with provision being made according to the invention for it to be possible to cool an outlet opening, through which air together with the fluid driven out of the drying material can enter the interior, when the air together with the fluid driven out of the drying material enters the interior.

Other developments are set out in the subclaims.

The invention and its developments are described in more detail below with reference to drawings, in which:

FIG. 1 shows a schematic diagram of an exemplary embodiment of an inventive dishwasher with a sorption drying system,

FIG. 2 shows a schematic diagram of the temperature profile during a first exemplary embodiment of an inventive wash program run,

FIG. 3 shows a schematic diagram of the temperature profile of a further, second exemplary embodiment of an inventive wash program run, and

FIG. 4 shows a schematic diagram of the temperature profile of a further, third exemplary embodiment of an inventive wash program run.

Reference is made first to FIG. 1.

A dishwasher GS, configured in the present exemplary embodiment as a household dishwasher, has an interior IR serving as a washing container, which can be opened and closed for loading and unloading by means of a door (not shown) hinged to the dishwasher GS in a pivotable manner. Racks GK for holding items to be washed are provided in the interior IR of the dishwasher GS, it being possible to pull said racks GK out of the interior IR of the dishwasher GS to facilitate loading and unloading.

To clean the items to be washed supported in the racks GK, means for applying fluid to the items to be washed configured as spray arms SA are provided in the interior IR of the dishwasher GS, it being possible for the fluid to be for example water mixed with detergents or rinse aid, in order thus to bring about a cleaning action or streak-free drying. The fluid flowing off the items being washed collects in a pump sump PS, which is disposed in the base region of the interior IR of the dishwasher GS.

The spray arms SA are connected in a fluid-conducting manner by way of a supply line ZL to a circulation pump UP, which is disposed along with other components of the dishwasher GS in a base assembly BO beneath the interior IR of the dishwasher GS. During operation, i.e. when the circulation pump UP is running, the circulation pump UP sucks up the fluid collected in the pump sump PS and conveys it through the supply line ZL to the spray arms SA. To heat the fluid circulated by operation of the circulation pump UP, the circulation pump has an integrated water heater WZ for heating the fluid. Alternatively a separate flow-through heater or another water heater can be provided in addition to the circulation pump UP. A drain pump LP is provided to empty the interior IR of the dishwasher GS, being likewise connected in a fluid-conducting manner to the pump sump PS and being able to be connected by way of a discharge line EL to a house-side waste water disposal network.

The dishwasher GS further features a sorption drying system, which can be used to dry cleaned items disposed in the racks GR at the end of a wash program run. To this end a sorption container SB is provided in the base assembly BO, being connected in an air-conducting manner to an inlet EI by way of an air channel LK, with a fan LT being provided to generate a forced throughflow. To convey the air sucked in through the inlet EI and conveyed into the sorption container by the fan LT back into the interior IR of the dishwasher GS, an outlet opening AU is provided in the base region of the interior IR of the dishwasher GS.

To bring about drying of cleaned items, the fan LT sucks in air from the interior IR of the dishwasher GS, conducts it through the sorption container SB and back through the outlet opening AU into the interior IR of the dishwasher GS. In order to dry the circulated air in this process, a drying means for performing exothermic drying is provided in the sorption container SB. This is a reversibly dehydratable drying material, e.g. zeolite, that absorbs water due to its hydroscopic nature, in which process thermal energy is simultaneously released. This released energy causes the circulated air to be heated, thereby raising the moisture absorption capacity of the circulated air. At the end of a drying process a quantity of fluid is stored in the drying material ZEO.

To restore the absorption capacity of the drying means ZEO for a new wash program run, an air heater HZ is provided, which is disposed in the sorption container SB in the present exemplary embodiment. It is however also possible to dispose an air heater outside the sorption container SB, e.g. in the air channel LK, to bring about heating of the air conveyed into the sorption container SB. An air flow generated using the fan LT is heated to drive out the quantity of fluid stored in the drying material ZEO, so that the drying material ZEO can be heated to temperatures at which the quantity of water stored in the drying material ZEO can be released again.

We will now look at FIGS. 2 to 4.

To wash and dry items to be washed, dishwashers GS run through wash programs that consist of a plurality of program steps that are run through one after the other. Such a program can consist of the program steps prewash V, wash R, intermediate rinse Z, final rinse K and drying T, it being possible also to omit individual program steps such as prewash V or intermediate rinse Z while it is also possible to run individual program steps a number of times, e.g. intermediate rinse Z. During the prewash V water with no detergent added for example is applied to the items to be washed, this taking place either with unheated water or with water heated using a heater. To this end water that has been stored in a water tank (not shown) can be used. Such a water tank can be connected in a thermally conducting manner to the environment of the dishwasher, so that fluid stored in an intermediate fashion in the water tank, e.g. water from a house-side supply system, can be heated to ambient temperature. In the washing step R the items to be washed are cleaned by the application of water containing detergents, i.e. detergent is added during the washing step. The fluid is also heated in order thus to enhance the cleaning action of the detergent. The washing step R here is made up of a heating phase P1, P2, in which the fluid in the dishwasher GS is heated by heating means, until a predefined maximum temperature is reached and a subsequent post-wash phase, during which the heating means are switched off and the slowly cooling fluid is circulated by means of the circulation pump UP. In the program step intermediate rinse Z fluid is applied to the items to be washed, to convey dirt residues out of the dishwasher GS. The next program step is the final rinse K in preparation for the drying program step T, in which water containing rinse aid is circulated by means of the circulation pump and applied to the now cleaned items by way of the spray arms SA. The program step drying T then follows, in which fluid is no longer applied to the items but operation of the fan LT causes an air flow circulating through the interior IR of the dishwasher GS and the sorption container SB to be generated. A full or at least partial fluid change can be effected between the individual program steps, in other words the dishwasher GS is emptied by means of the drain pump LP and the discharge line EL and refilled by a supply line (not shown) that establishes a connection to a house-side supply system.

With the wash program sequence according to FIG. 2 fluid is only heated in the program step wash R. Starting from a start temperature T0 during a first phase P1 the fluid circulated using the circulation pump UP is first heated by the air heater HZ in the sorption container SB to a maximum temperature T1, with the fan LT generating an air flow circulating through the interior IR of the dishwasher GS at the same time. The air heater LZ heats the drying material ZEO in the sorption container SB to temperatures at which the quantity of water stored in the drying material ZEO is driven out of the drying material ZEO and conveyed through the outlet opening AU in the interior IR of the dishwasher GS. This quantity of fluid is heated by the action of the air heater HZ and when mixed with the fluid already circulated by means of the circulation pump UP heats the overall quantity of fluid in the interior IR of the dishwasher GS.

The use of the air heater HZ during the program step wash R to heat up to the first temperature T1 ensures that the drying material ZEO can be reliably and completely desorbed by the circulation of relatively cold and dry air from the interior IR of the dishwasher GS. Instead of a rigid wash program sequence, in which a desorption process is performed in a first program segment, in which fluid is heated, in an alternative exemplary embodiment provision can also be made for evaluating parameters that influence the desorption process, to determine the time point for performing desorption. These parameters can be the air temperature and the water intake temperature. For example a desorption process can take place in a program step wash or final rinse or even during the program step prewash if expedient.

During desorption by means of the air heater HZ the outlet opening AU in the interior IR of the dishwasher GS is cooled, to ensure that the heat output of the air heater HZ does not cause excessive heating of the outlet opening HZ with overheating damage.

To this end during operation of the air heater HZ, i.e. during phase P1 for example, the circulation pump UP is operated in such a manner that fluid is conveyed by the circulation pump from the pump sump PS through the supply line to the spray arms SA. This causes the spray arms SA to rotate and the spraying of the outlet opening AU, in particular a cap covering the outlet opening AU, with fluid brings about cooling of the same.

In a next phase P2 of the program step wash R the water heater WZ heats the quantity of fluid from the first temperature T1 to the second temperature T2.

To enhance the cleaning action during the program step wash R provision is made to increase the spray pressure of the jets of water coming out of the spray arms SA by increasing the speed of the circulation pump UP. To this end during the program step wash R in the post-wash phase NA the quantity of fluid circulated by the circulation pump UP is increased by means of a top-up step, for example at time point t1 (see FIG. 2) and the speed of the circulation pump UP is then increased, e.g. continuously until the circulation pump again operates in true running conditions, in other words does not take in air bubbles during operation, which reduces the delivery rate of the circulation pump UP and causes unwanted noise to develop. It thus becomes possible to take account of the quantity of fluid that was stored in the drying material ZEO and is released during desorption when setting the quantity of top-up fluid, thereby reducing the overall water requirement whilst still improving cleaning performance.

A run-off phase AB is provided between the program step final rinse K and the program step drying T (see FIG. 2), during which fluid adhering to the washed items, i.e. water containing rinse aid, can run off the items in the dishwasher due to gravity and collect in the pump sump PS of the interior IR of the dishwasher GS. This reduces the quantity of fluid to be absorbed by the sorption drying system and thus the duration of the program step drying T.

Before this run-off phase AB, in other words at the end of the program step final rinse K, a pump-out process takes place, in which the fluid containing rinse aid is conveyed by means of the drain pump LP through the discharge line EL into a house-side waste water disposal system. The run-off phase AB follows, during which neither the circulation pump UP nor the drain pump LP, nor the fan LT nor any of the above-mentioned heaters HZ, WZ is in operation. After the end of this run-off phase AB the program step drying T starts by starting up the fan LT, so that an air flow circulating through the interior IR of the dishwasher and the sorption container SB is generated to dry the washed items in the racks GK. At the end of the program step drying T a further pump-out process takes place by means of the drain pump LP, by means of which a residual quantity of fluid is conveyed out of the dishwasher GS through the discharge line EL into a house-side waste water disposal system. Alternatively provision can also be made to perform a further pump-out process additionally or alternatively at the start of the program step drying T.

In the wash program according to FIGS. 3 and 4 fluid is heated in the first of the program steps, the program step prewash V. To this end the air heater HZ heats fluid from a start temperature T0 during a phase P1′ to a temperature T1′, in which, as described above, an air flow circulating through the interior IR of the dishwasher GS and the sorption container SB is generated by means of the fan LT. Once the temperature T1' is reached, the air heater HZ is deactivated. At this time point the drying material ZEO is not yet completely desorbed, in other words a residual quantity of water is stored in the drying material ZEO. To drive this residual quantity of water out of the drying material ZEO and thus have a drying material ZEO with full water absorption capacity available again at the start of the program step drying T, in the next program step wash R the fluid is first heated by means of the air heater HZ to a temperature T1 and then by operation of the water heater to the temperature T2. In other words the desorption phase of the drying means ZEO in the sorption container SB is split into two and divided between two program steps, namely the program step prewash V and the program step wash R.

To enhance the cleaning action by further increasing the temperature, provision can be made for a further phase P3 (see FIG. 3), during which the fluid is further heated to a temperature T3 using the water heater WZ.

To improve the drying result at the end of the program step drying T, with the exemplary embodiments according to FIGS. 3 and 4 provision is made for the fluid to be heated during the final rinse step K. To this end during a phase P4 fluid, which is water or water containing rinse aid, is heated to a temperature T4 by means of the water heater WZ. Alternatively, instead of the water heater the air heater HZ can also be used, in order for example to complete a desorption that has not yet been fully performed during the program run. Additionally during a further phase P5 further heating of the fluid to a temperature T5 can take place, to improve drying using the sorption drying system.

LIST OF REFERENCE CHARACTERS

-   AB Run-off phase -   AU Outlet opening -   BO Base assembly -   EI Inlet -   EL Disposal line -   GK Rack -   GS Dishwasher -   HZ Air heater -   IR Interior -   LK Air channel -   LP Drain pump -   LT Fan -   NA Post-wash phase -   P1′ Phase 1′ -   P1 Phase 1 -   P2 Phase 2 -   P3 Phase 3 -   P4 Phase 4 -   P5 Phase 5 -   PS Pump sump -   SA Spray arm -   SB Sorption container -   t1 Top-up time point -   T0 Start temperature -   T1′ Temperature -   T1 Temperature -   T2 Temperature -   T3 Temperature -   T4 Temperature -   T5 Temperature -   UP Circulation pump -   WZ Water heater -   ZEO Drying material -   ZL Supply line 

1-18. (canceled)
 19. A method for operating a dishwasher, the method comprising: at least periodically applying a heated fluid to items to be washed that are supported in an interior of the dishwasher; in order to heat the fluid, first conducting air through a drying material suitable for exothermic drying and then conducting the air, together with the heated fluid driven out of the drying material, through an outlet opening through which the air, together with the heated fluid driven out of the drying material, enters the interior of the dishwasher; and cooling the outlet opening.
 20. The dishwasher of claim 19, wherein the dishwasher is a household dishwasher.
 21. The method of claim 19, wherein the outlet opening is wet with a cooling agent in order to cool the outlet opening.
 22. The method of claim 21, wherein the cooling agent contains water.
 23. The method of claim 21, wherein the cooling agent is circulated in a closed circuit.
 24. The method of claim 21, wherein the cooling agent is circulated by a circulation pump in order to apply the heated fluid to the items to be washed.
 25. The method of claim 24, wherein the circulation pump is operated at a lower speed when the outlet opening is cooled than when the heated fluid is applied to the items to be washed.
 26. The method of claim 25, wherein the air is conducted in a closed circuit from the interior of the dishwasher through the drying material and back through the outlet opening into the interior of the dishwasher.
 27. The method of claim 19, wherein the air flows through the drying material by a forced throughflow.
 28. The method of claim 27, wherein the forced throughflow is brought about by a fan.
 29. The method of claim 19, wherein the drying material is reversibly dehydratable.
 30. The method of claim 29, wherein the reversibly dehydratable material is zeolite.
 31. A dishwasher, comprising: means for at least periodically applying a heated fluid to items to be washed that are supported in an interior of the dishwasher; and a drying material suitable for exothermic drying to heat the fluid; wherein, in order to heat the fluid, air is first conducted through the drying material; wherein the air is then conducted, together with heated fluid driven out of the drying material, through an outlet opening through which the air, together with the heated fluid driven out of the drying material, enters the interior of the dishwasher; and wherein the outlet opening is cooled when the air, together with the fluid driven out of the drying material, enters the interior of the dishwasher.
 32. The dishwasher of claim 31, wherein the dishwasher is a household dishwasher.
 33. The dishwasher of claim 31, wherein the outlet opening is wet with a cooling agent in order to cool the outlet opening.
 34. The dishwasher of claim 33, wherein the cooling agent contains water.
 35. The dishwasher of claim 33, further comprising a closed circuit in which the cooling agent is circulated.
 36. The dishwasher of claim 35, further comprising a circulation pump to apply the heated fluid to the items to be washed, wherein the circulation pump circulates the cooling agent.
 37. The dishwasher of claim 36, wherein the circulation pump is operated at a lower speed when the outlet opening is cooled than when the heated is fluid is applied to the items to be washed.
 38. The dishwasher of claim 31, further comprising a closed circuit, in which the air from the interior of the dishwasher is conducted through the drying material and back through the outlet opening into the interior of the dishwasher.
 39. The dishwasher of claim 31, further comprising means for forcing a throughflow of the air through the drying material.
 40. The dishwasher of claim 39, wherein the means for forcing the throughflow of the air through the drying material is a fan.
 41. The dishwasher of claim 31, wherein the drying material is reversibly dehydratable.
 42. The dishwasher of claim 41, wherein the reversibly dehydratable drying material is zeolite. 